ICE Instantiating defaulted assignment with explicit object parameter of base type

[JohelEGP]

See https://compiler-explorer.com/z/KsvovEG1G.

struct Base {};
struct S : Base {
    int j;
    S& operator=(this Base& self, const S&) = default;
};

void test() {
    S s;
    s = s;
}

<source>:9:7: warning: explicitly assigning value of variable of type 'S' to itself [-Wself-assign-overloaded]
    9 |     s = s;
      |     ~ ^ ~
clang++: /root/llvm-project/clang/lib/Sema/SemaDeclCXX.cpp:14386: static clang::Expr* {anonymous}::ExprBuilder::assertNotNull(clang::Expr*): Assertion `E && "Expression construction must not fail."' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++26 -stdlib=libc++ -pedantic-errors -Wall -Wextra -Wconversion <source> -isystem/opt/compiler-explorer/libs/boost_1_82_0
1.	<source>:9:10: current parser token ';'
2.	<source>:7:13: parsing function body 'test'
3.	<source>:7:13: in compound statement ('{}')
 #0 0x000000000372ef98 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x372ef98)
 #1 0x000000000372cc5c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x372cc5c)
 #2 0x0000000003675578 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f3b76110420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f3b75bd300b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f3b75bb2859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f3b75bb2729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f3b75bc3fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00000000062896f3 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62896f3)
 #9 0x0000000006289877 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6289877)
#10 0x000000000629c5ab buildSingleCopyAssignRecursively(clang::Sema&, clang::SourceLocation, clang::QualType, (anonymous namespace)::ExprBuilder const&, (anonymous namespace)::ExprBuilder const&, bool, bool, unsigned int) SemaDeclCXX.cpp:0:0
#11 0x000000000629d027 buildSingleCopyAssign(clang::Sema&, clang::SourceLocation, clang::QualType, (anonymous namespace)::ExprBuilder const&, (anonymous namespace)::ExprBuilder const&, bool, bool) SemaDeclCXX.cpp:0:0
#12 0x00000000062e9d41 clang::Sema::DefineImplicitCopyAssignment(clang::SourceLocation, clang::CXXMethodDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62e9d41)
#13 0x0000000006421aa5 void llvm::function_ref<void ()>::callback_fn<clang::Sema::MarkFunctionReferenced(clang::SourceLocation, clang::FunctionDecl*, bool)::'lambda'()>(long) SemaExpr.cpp:0:0
#14 0x0000000005ff1731 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ff1731)
#15 0x0000000006418a84 clang::Sema::MarkFunctionReferenced(clang::SourceLocation, clang::FunctionDecl*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6418a84)
#16 0x0000000006418fcd MarkExprReferenced(clang::Sema&, clang::SourceLocation, clang::Decl*, clang::Expr*, bool, llvm::DenseMap<clang::VarDecl const*, int, llvm::DenseMapInfo<clang::VarDecl const*, void>, llvm::detail::DenseMapPair<clang::VarDecl const*, int>>&) SemaExpr.cpp:0:0
#17 0x000000000676c26a CreateFunctionRefExpr(clang::Sema&, clang::FunctionDecl*, clang::NamedDecl*, clang::Expr const*, bool, clang::SourceLocation, clang::DeclarationNameLoc const&) SemaOverload.cpp:0:0
#18 0x00000000067a71a6 clang::Sema::CreateOverloadedBinOp(clang::SourceLocation, clang::BinaryOperatorKind, clang::UnresolvedSetImpl const&, clang::Expr*, clang::Expr*, bool, bool, clang::FunctionDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67a71a6)
#19 0x00000000063bcb4e BuildOverloadedBinOp(clang::Sema&, clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) SemaExpr.cpp:0:0
#20 0x0000000006441157 clang::Sema::BuildBinOp(clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6441157)
#21 0x0000000006441723 clang::Sema::ActOnBinOp(clang::Scope*, clang::SourceLocation, clang::tok::TokenKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6441723)
#22 0x0000000005f0ab6b clang::Parser::ParseRHSOfBinaryExpression(clang::ActionResult<clang::Expr*, true>, clang::prec::Level) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f0ab6b)
#23 0x0000000005f0e0c9 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f0e0c9)
#24 0x0000000005f88c97 clang::Parser::ParseExprStatement(clang::Parser::ParsedStmtContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f88c97)
#25 0x0000000005f7f32d clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f7f32d)
#26 0x0000000005f80168 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f80168)
#27 0x0000000005f810a9 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f810a9)
#28 0x0000000005f829ca clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f829ca)
#29 0x0000000005eb06e1 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eb06e1)
#30 0x0000000005ed7bf8 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ed7bf8)
#31 0x0000000005ea4b4b clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea4b4b)
#32 0x0000000005ea527f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#33 0x0000000005eacc24 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eacc24)
#34 0x0000000005ead44d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ead44d)
#35 0x0000000005ea04fa clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea04fa)
#36 0x000000000499ab88 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x499ab88)
#37 0x00000000041fe849 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41fe849)
#38 0x000000000417fd1e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x417fd1e)
#39 0x00000000042dd9ee clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42dd9ee)
#40 0x0000000000bef806 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbef806)
#41 0x0000000000be70ca ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#42 0x0000000003fdbf69 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#43 0x0000000003675a24 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3675a24)
#44 0x0000000003fdc55f clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#45 0x0000000003fa4725 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fa4725)
#46 0x0000000003fa518d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fa518d)
#47 0x0000000003fad0b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fad0b5)
#48 0x0000000000beccac clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbeccac)
#49 0x0000000000ae6e61 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xae6e61)
#50 0x00007f3b75bb4083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#51 0x0000000000be6bae _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbe6bae)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

I hear that EDG gets it right.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Johel Ernesto Guerrero Peña (JohelEGP)

See <https://compiler-explorer.com/z/KsvovEG1G>. ```C++ struct Base {}; struct S : Base { int j; S& operator=(this Base& self, const S&) = default; };

void test() {
S s;
s = s;
}

```output
<source>:9:7: warning: explicitly assigning value of variable of type 'S' to itself [-Wself-assign-overloaded]
    9 |     s = s;
      |     ~ ^ ~
clang++: /root/llvm-project/clang/lib/Sema/SemaDeclCXX.cpp:14386: static clang::Expr* {anonymous}::ExprBuilder::assertNotNull(clang::Expr*): Assertion `E && "Expression construction must not fail."' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++26 -stdlib=libc++ -pedantic-errors -Wall -Wextra -Wconversion <source> -isystem/opt/compiler-explorer/libs/boost_1_82_0
1.	<source>:9:10: current parser token ';'
2.	<source>:7:13: parsing function body 'test'
3.	<source>:7:13: in compound statement ('{}')
 #<!-- -->0 0x000000000372ef98 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x372ef98)
 #<!-- -->1 0x000000000372cc5c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x372cc5c)
 #<!-- -->2 0x0000000003675578 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007f3b76110420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #<!-- -->4 0x00007f3b75bd300b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #<!-- -->5 0x00007f3b75bb2859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #<!-- -->6 0x00007f3b75bb2729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #<!-- -->7 0x00007f3b75bc3fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #<!-- -->8 0x00000000062896f3 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62896f3)
 #<!-- -->9 0x0000000006289877 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6289877)
#<!-- -->10 0x000000000629c5ab buildSingleCopyAssignRecursively(clang::Sema&amp;, clang::SourceLocation, clang::QualType, (anonymous namespace)::ExprBuilder const&amp;, (anonymous namespace)::ExprBuilder const&amp;, bool, bool, unsigned int) SemaDeclCXX.cpp:0:0
#<!-- -->11 0x000000000629d027 buildSingleCopyAssign(clang::Sema&amp;, clang::SourceLocation, clang::QualType, (anonymous namespace)::ExprBuilder const&amp;, (anonymous namespace)::ExprBuilder const&amp;, bool, bool) SemaDeclCXX.cpp:0:0
#<!-- -->12 0x00000000062e9d41 clang::Sema::DefineImplicitCopyAssignment(clang::SourceLocation, clang::CXXMethodDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62e9d41)
#<!-- -->13 0x0000000006421aa5 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::Sema::MarkFunctionReferenced(clang::SourceLocation, clang::FunctionDecl*, bool)::'lambda'()&gt;(long) SemaExpr.cpp:0:0
#<!-- -->14 0x0000000005ff1731 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ff1731)
#<!-- -->15 0x0000000006418a84 clang::Sema::MarkFunctionReferenced(clang::SourceLocation, clang::FunctionDecl*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6418a84)
#<!-- -->16 0x0000000006418fcd MarkExprReferenced(clang::Sema&amp;, clang::SourceLocation, clang::Decl*, clang::Expr*, bool, llvm::DenseMap&lt;clang::VarDecl const*, int, llvm::DenseMapInfo&lt;clang::VarDecl const*, void&gt;, llvm::detail::DenseMapPair&lt;clang::VarDecl const*, int&gt;&gt;&amp;) SemaExpr.cpp:0:0
#<!-- -->17 0x000000000676c26a CreateFunctionRefExpr(clang::Sema&amp;, clang::FunctionDecl*, clang::NamedDecl*, clang::Expr const*, bool, clang::SourceLocation, clang::DeclarationNameLoc const&amp;) SemaOverload.cpp:0:0
#<!-- -->18 0x00000000067a71a6 clang::Sema::CreateOverloadedBinOp(clang::SourceLocation, clang::BinaryOperatorKind, clang::UnresolvedSetImpl const&amp;, clang::Expr*, clang::Expr*, bool, bool, clang::FunctionDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67a71a6)
#<!-- -->19 0x00000000063bcb4e BuildOverloadedBinOp(clang::Sema&amp;, clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) SemaExpr.cpp:0:0
#<!-- -->20 0x0000000006441157 clang::Sema::BuildBinOp(clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6441157)
#<!-- -->21 0x0000000006441723 clang::Sema::ActOnBinOp(clang::Scope*, clang::SourceLocation, clang::tok::TokenKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6441723)
#<!-- -->22 0x0000000005f0ab6b clang::Parser::ParseRHSOfBinaryExpression(clang::ActionResult&lt;clang::Expr*, true&gt;, clang::prec::Level) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f0ab6b)
#<!-- -->23 0x0000000005f0e0c9 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f0e0c9)
#<!-- -->24 0x0000000005f88c97 clang::Parser::ParseExprStatement(clang::Parser::ParsedStmtContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f88c97)
#<!-- -->25 0x0000000005f7f32d clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f7f32d)
#<!-- -->26 0x0000000005f80168 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector&lt;clang::Stmt*, 32u&gt;&amp;, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f80168)
#<!-- -->27 0x0000000005f810a9 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f810a9)
#<!-- -->28 0x0000000005f829ca clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5f829ca)
#<!-- -->29 0x0000000005eb06e1 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&amp;, clang::Parser::ParsedTemplateInfo const&amp;, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eb06e1)
#<!-- -->30 0x0000000005ed7bf8 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&amp;, clang::DeclaratorContext, clang::ParsedAttributes&amp;, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ed7bf8)
#<!-- -->31 0x0000000005ea4b4b clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec&amp;, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea4b4b)
#<!-- -->32 0x0000000005ea527f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#<!-- -->33 0x0000000005eacc24 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eacc24)
#<!-- -->34 0x0000000005ead44d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ead44d)
#<!-- -->35 0x0000000005ea04fa clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ea04fa)
#<!-- -->36 0x000000000499ab88 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x499ab88)
#<!-- -->37 0x00000000041fe849 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41fe849)
#<!-- -->38 0x000000000417fd1e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x417fd1e)
#<!-- -->39 0x00000000042dd9ee clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42dd9ee)
#<!-- -->40 0x0000000000bef806 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbef806)
#<!-- -->41 0x0000000000be70ca ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->42 0x0000000003fdbf69 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->43 0x0000000003675a24 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3675a24)
#<!-- -->44 0x0000000003fdc55f clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->45 0x0000000003fa4725 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fa4725)
#<!-- -->46 0x0000000003fa518d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fa518d)
#<!-- -->47 0x0000000003fad0b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3fad0b5)
#<!-- -->48 0x0000000000beccac clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbeccac)
#<!-- -->49 0x0000000000ae6e61 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xae6e61)
#<!-- -->50 0x00007f3b75bb4083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#<!-- -->51 0x0000000000be6bae _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbe6bae)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

I hear that EDG gets it right.

[shafik]

This is broke in trunk but not in clang-17: https://compiler-explorer.com/z/6PnbWYKsK

I feel like there was a recent fix in this area but I can't find it. CC @cor3ntin @AaronBallman

[Fznamznon]

This is broke in trunk but not in clang-17

Is that because clang-17 doesn't implement "deducing this" yet?

changing example to

struct Base {};
struct S : Base {
    int j;
    S& operator=(this S& self, const S&) = default;
};
void test() {
    S s;
    s = s;
}

makes the crash go away.

[JohelEGP]

S& operator=(this S& self, const S&) = default;
The bug is about not having S as this, but its base type.

[cor3ntin]

https://eel.is/c++draft/dcl.fct.def.default#2.2

if F2 has an implicit object parameter of type “reference to C”, F1 may be an explicit object member function whose explicit object parameter is of (possibly different) type “reference to C”, in which case the type of F1 would differ from the type of F2 in that the type of F1 has an additional parameter;

What is "(possibly different)" trying to say? IE, i am not sure it is reasonable for the above code to be well-formed.
it would make sense to limit to the same unqualified type.

[AaronBallman]

https://eel.is/c++draft/dcl.fct.def.default#2.2

if F2 has an implicit object parameter of type “reference to C”, F1 may be an explicit object member function whose explicit object parameter is of (possibly different) type “reference to C”, in which case the type of F1 would differ from the type of F2 in that the type of F1 has an additional parameter;

What is "(possibly different)" trying to say? IE, i am not sure it is reasonable for the above code to be well-formed. it would make sense to limit to the same unqualified type.

I think it's trying to call out that F2's implicit object parameter type and F1's explicit object parameter type may be different. Isn't it analogous to this situation without special member functions: https://godbolt.org/z/bqh1vv6fE ?